The present invention relates to an interface unit for use with pneumatic drills and, in particular, an interface unit which is adaptable for use on different types of commercially available drills having axially extendable tool holders.
Pneumatic drills having extendable tool holders which rotate as they extend and retract are peculiarly adapted for performing repetitive operations on articles placed before them. Such drills are well adapted for assembly-line type use, particularly where the access space to the required machining area is limited. Such drills are commercially available from a number of manufacturers.
A problem with such drills is that they required custom-designed interface piping, including electrically operated solenoid valves, in order to allow for automatic operation by a programmable controller. Furthermore, such conventional drills fall within two general categories: A first category including those drills which are actuated by switching a supply of compressed air to one port of the drill head, with the other such port being continuously vented to atmosphere (`thru head` type drills); and a second category including those drills which are actuated by venting one port while continuously deadheading or blocking the other port (`valve in head` type drills). Because of this division, it has previously been necessary to tailor the pneumatic piping to the particular type of drill purchased.
Another problem has been attachment of interface units and tool holder position indicators to the drills. Previously, custom-designed bracketry and attaching means have been required which, not only include custom parts, but are often bulky and take up too much space to use in limited machining areas. Furthermore, improvements in reliability, repairability and adjustability are desirable.